In 2009, NASA launched the Kepler spacecraft to look for Earth-like planets orbiting around distant stars that resemble our Sun. Cameras on board Kepler analyze the vibrations – or oscillations – of stars, and transmit data back to astronomers on Earth. By analyzing how a star oscillates, researchers can learn a lot about the mass and radius of that star.

Now, new data from the Kepler mission is giving researchers a good look at the internal structures of many distant stars. This week in Science, William Chaplin and colleagues describe how they used data from Kepler to measure the oscillations of 500 stars that vibrate like our Sun. (Before their study, astronomers had only detected these Sun-like oscillations in a total of 25 stars!)

Chaplin and his colleagues then used their new measurements from Kepler to test some of the most popular theories about how stars grow and evolve. The researchers used the stars' oscillations to estimate the mass, radii and age of each of the stars.

Based on the new data from Kepler, the radii of the stars turned out to be what was expected. However, the researchers were surprised to find that the mass of the stars they calculated was lower than models had predicted.

In light of these findings, Chaplin and his colleagues say that the current models of star formation should be revised in order to fix the mass-radius relationship and to better understand how stars evolve in our galaxy.